Hand Tools

Mark HenneburyControlled chip cutterhead for planers and jointers
US 4353400 A

ABSTRACT
Cutterheads operating in the gap between in-feed and out-feed tables of planers, jointers and the like wood cutting apparatus are provided with a body of increased diameter and a gib having a chipbreaker pocket shape that will expose only a minimum projection of the knife before the chip must curl into the pocket thereby reducing the potential bite of a kick back such as might occur by a tipping of the wood workpiece or by a pull out of the wood grain during the feeding of the workpiece to the cutting knives. The knives of the cutterhead protrude only as much above the cutterhead body as is required not to interfere with the advance of the workpiece per revolution of each knife, the gib is positioned with its chipbreaker pocket down from the tip of the knife no further than is necessary for chip thickness, and the chipbreaker pocket has a radius just sufficient to accommodate the curled chip at the maximum depth of the cut. Since the cutterhead body is larger and the blade exposure is less, the gap between the tables of the planer or jointer and the cutterhead is reduced. In addition, since the exposure of the knives above the body of the cutterhead is reduced, a lesser fan effect is achieved to decrease noise levels when the planer or jointer is idling. The cutterheads and gibs of this invention thus reduces the possibility of kick back, reduce the severity of kick back should it occur, reduce the severity of injury should contact with the blades occur, reduce chipping out and grain pull out to improve the quality of cut on wood burl or other swirl grain type wood workpieces and produce a tight curl chip that is easily handled by dust collectors.